From the article: “The paper is also silent about how the layers were dated. There is no mention of radiometric dating or radiocarbon (which would not be expected to survive past 100,000 years, anyway). Perhaps the dates were inferred by the layers they were in, according to the geologic column.”
“However the layers were dated, the millions-of-years dates are problematic not just because wood would not be expected to survive so long. Another problem is why so little wood was detected. There was plenty scattered throughout the cores, to be sure, but 19 million years is a long time.”
Since the article refers to multiple sand layers interspersing the mud layers, it is not clear if some of the wood might be young enough to test with C14. The pieces are in mm to cm sizes and dark. Also a thousand feet from shore and dating back as far as 19 million years. Are there other ways besides C14 to test very old wood? I suppose it would be the anoxic conditions that would preserve it as wood rather than fossil.
There's a 50K limit for RC dating; greater sensitivity is poosible out to about 60K I believe, but in practice, in the wild, the samples would have to be demonstrably pristine, a condition that does not alas persist in the oceans. Other radiometric methods would work, but on minerals rather than wood.